Conventional weft inserted warp knit fabrics have many desirable properties, and desirable production procedures, so that the use thereof for large textile panels, particularly water and air impervious large textile panels such as pond liners, roof reinforcements, tarpaulins, and air supported panels, is desirable. However there have been practical difficulties associated with the formation of weft inserted warp knit fabric into large textile panels. These difficulties primarily occur because there is insufficient cohesion between the yarn systems to provide the necessary seam strength when widths of the fabric are attached to each other. Even after improving the adhesive properties of the fabric by chemical finishing, and coating, sufficient seam strength cannot be achieved for many applications. For instance when it is desired to attach such fabric structures together by buffing the selvedge edges and then utilizing a cement adhesive, the buffing destroys the polymer coating and portions of the fiber bundle, leading to reduced strength and service life. Heat sealing the lapped seam area accelerates the aging process of the polymer by oxidation, and the fibers of the fabric are degraded by the same process. Ultrasonically fusing the lapped areas to form a seam degrades the polymers in a manner similar to heat sealing, with the associated reduced tearing strength and service life.
According to the present invention, the problems inherent in the utilization of weft inserted warp knit fabrics in the construction of large textile panels--as set forth above--are substantially overcome, and large textile panels may be produced that have good seam strength and tear resistance, and long service life. Large textile panels according to the invention are suitable as pond liners, roof reinforcements, tarpaulins, air supported panels, or for other uses where air and water impervious large textile panels are desired.
The basic feature according to the present invention that allows the disadvantages of the prior art to be overcome is the provision of a tough reinforcing substrate along the selvedge edges of the small weft inserted warp knit fabric panels that are produced (and subsequently joined to form large panels). The substrate strips are spaced from each other along the width of the fabric, but extend a sufficient distance along the selvedge edges to provide the desired reinforcement during joining of the edges together, whether by buffing and subsequent application of cement adhesive, or ultrasonic or thermal fusing. The substrate strips are stitched to the weft inserted warp knit fabric during the normal construction thereof, and for some uses may also be provided at intermediate portions along the width of the fabric, parallel to the selvedge edge strips and spaced therefrom. Typical substrate materials utilizable in the practice of the invention include nonwoven fabrics, paper, thermoplastic films, knit, or woven fabrics, as long as they have the necessary toughness to perform the reinforcing function.
In addition to overcoming the drawbacks in the prior art, as discussed above, by the practice of the present invention chemical finishing of the textile panels is facilitated. The fabric of the small textile panels may be securely clamped at each selvedge by the pins or clips of a tenter frame during chemical finishing. Typically finishing would be accomplished by applying an adhesive system, such as an isocyanate, Resorcinol formaldehyde, or Silane, and then applying a thermoset or thermoplastic polymer coating over the adhesive system.
According to the invention, the adjacent selvedge edges of small panels are overlapped, and then attached to each other to form a final large textile panel. The overlapping edges may be cascaded to facilitate buffing and cement application, and then underlying edges turned back to provide attachment to the associated adjacent edges.
It is the primary object of the present invention to provide large textile panels formed from smaller panels of weft inserted warp knit fabric--and a method of production thereof--that have good seam strength, good tear resistance, and long service life. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.